This invention relates to couplers for attaching excavator buckets and other tools to heavy construction equipment.
Quick couplers have been widely used with excavating equipment, e.g. hydraulic excavators (backhoes), to allow individual pieces of equipment to be used with a variety of tools, e.g., different buckets, grapples and the like, without extended downtime for changing tools. Conventional quick couplers are described, e.g., in U.S. Pat. Nos. 4,726,731 and 3,231,116. Quick couplers typically consist of a pair of spaced parallel plates, the plates defining holes for fixed attachment of the coupler to the end of a backhoe. The plates also define a first slot facing generally forward to engage a first pin on the bucket or tool, and a second slot, facing generally downward (i.e., disposed at 90xc2x0 to the first slot) to engage a second pin on the bucket or tool. In operation, the first pin is engaged in the first slot. The coupler is then rotated about the longitudinal axis of the first pin to engage the second pin in the second slot. The coupler and tool are thereafter secured together by engagement, e.g., of a coupler gate with the second pin. This coupler gate is typically pivotally mounted to a pin on the coupler such that it pivots about a horizontal axis parallel to the longitudinal axes of the first and second slots/pins. These conventional couplers can be rendered virtually unusable by a relatively small degree of wear in the slots. This problem of wear in a conventional coupler was addressed in Arnold U.S. Pat. No. 5,332,353, the complete disclosure of which is incorporated herein by reference.
According to the invention, a quick coupler for attaching a tool having first and second generally parallel pins to an excavator or the like comprises a coupler body with a pair of sidewall plate members disposed spaced from and generally parallel to each other, and a set of cross members extending generally between the sidewall plate members, the set of cross members comprising at least first and second cross members spaced from each other and defining a slide port, and the pair of sidewall plate members defining a first slot facing in a first direction for engagement with the first pin of the tool and a second slot facing in a second direction transverse to the first direction for engagement with the second pin of the tool; and a lock plate assembly for releasable securing engagement of the second slot with the second pin comprising a lock plate moveable relative to the coupler body along a lock plate axis generally transverse to a longitudinal axis of the second pin, between a first lock plate position engaged with the slide port for obstructing the second slot to secure engagement of the second slot with the second pin, and a second lock plate position removed from obstruction of the second slot for removal or insertion of the second pin in engagement with the second slot; and a lock pin for releasable engagement with the lock plate, the lock pin being moveable between a first lock pin position engaged with the lock plate in manner to resist removal of the lock plate from the first lock plate position engaged with the slide port, and a second lock pin position releasing the lock plate.
Preferred embodiments of the invention may include one or more of the following additional features. The set of cross members further comprises at least a third cross member extending between the sidewall plate members and disposed generally along the lock plate axis and beyond the second slot relative to the first and second cross members and in a position to support the lock plate in the first lock plate position. The lock plate in the second lock plate position is removed from the lock plate port. The lock pin, in the first lock pin position is engaged between the lock plate and at least one cross member of the set of cross members. In the first lock plate position, the at least one cross member and the lock plate define aligned apertures, and the lock pin, in the first lock pin position, is engaged in the aligned apertures. The lock plate further defines a stop member disposed for engagement with at least one of the first and second cross members for terminating movement of the lock plate along the lock plate axis between the first lock plate position and the second lock plate position. The stop member defines a handle surface for the lock plate for movement from the second lock plate position toward the first lock plate position.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.